A non-methylammonium perovskite solar cell and a preparation method thereof

Abstract

The present application relates to a kind of perovskite solar cell without methylammonium calcium and its preparation method, belong to the preparation technical field of perovskite solar cell.The present application discloses a kind of perovskite solar cell without methylammonium calcium, from bottom to top, including substrate layer, lower charge transport layer (from bottom to top, including NiO x Thin film, poly [bis (4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) thin film and di-aluminum oxide film), perovskite layer, upper charge transport layer (PC 61 BM thin film and BCP thin film) and electrode.The perovskite solar cell without methylammonium calcium of the present application has power conversion efficiency up to 24.67%, and wet stability and thermal stability are improved, has the significance of active research in the aspect of organic salt engineering synergistic adjustment crystallization and bulk phase and interface defect.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell fabrication technology, and relates to a formammonium-free perovskite solar cell and its fabrication method. Background Technology

[0002] One of the key reasons for the poor quality of MA (methylammonium)-free perovskite films is the uncontrollable nucleation and crystal growth kinetics. Therefore, fine-tuning the nucleation rate and crystal growth rate is crucial for preparing high-quality perovskite films. In recent years, researchers have made great efforts to regulate the crystallization kinetics of CsFA (formamidinium cesium)-based MA-free perovskites.

[0003] Several strategies have proven effective in controlling the crystallization of perovskites, primarily including compositional engineering, solvent engineering, and additive engineering. Given Cs... x FA 1-x PbI3 is considered a relatively ideal perovskite composition, possessing the potential to simultaneously achieve high photoelectric conversion efficiency (PCE) and good long-term operational stability. However, further compositional engineering is needed to control the perovskite Cs... x FA 1-x Crystallization of PbI3 is impractical. Solvent engineering has been widely recognized as an effective method for controlling the crystallization of perovskite crystals. However, it seems insufficient to prepare high-quality CsFA-based MA-free perovskite films with excellent photovoltaic performance simply by adjusting the solvent. It is well known that solvents typically only serve to regulate crystallization, as they eventually evaporate from the perovskite film.

[0004] Conversely, non-volatile additives with appropriate functional groups can not only control crystallization kinetics but also effectively repair defects at grain boundaries (GBs). Among all crystallization-regulating additives, organic salts have attracted widespread attention due to their rich functional groups and structural diversity. For example, Meng et al. used a bifunctional additive (iBA-iBDTC) containing ammonium cations and dithiocarbamate anions to regulate the crystallization and defects of CsFA-based perovskite films, achieving a PCE as high as 24.25%. They further demonstrated that due to the interaction between iBA-iBDTC and PbI2, iBA-iBDTC can reduce the size and incoordination of Pb-I clusters and promote perovskite nucleation, which is beneficial for FA. + and Cs +Uniform integration into the Pb-I framework during crystallization. Li et al. reported a heterogeneous seed-induced crystallization regulation strategy, achieved by forming a low-solubility complex between di-tert-butyl(methyl)phosphotetrafluoroborate and PbI2. The improved device achieved a PCE of 24.0% and retained 84% of the original PCE after aging under light for 1400 h. Recently, Snaith et al. added dimethylammonium chloride to regulate the perovskite mesophase and achieved the preparation of high-quality CsFA-based MA-free perovskite films. Through this strategy, the crystallization sequence was controlled, and the grain size, texture, orientation, and crystallinity were finely adjusted. Therefore, the above results indicate that organic salts are very effective in regulating nucleation and crystal growth rates. Meanwhile, previous studies have also found that crystallization regulation is usually achieved through seeds or mesophases generated by the chemical interaction of organic salts and inorganic salt PbI2 via hydrogen bonds and / or ionic bonds. However, to date, no work has been reported on regulating crystallization through the mesophase between organic salts and FAI. Furthermore, since large-sized organic cations readily form two-dimensional perovskites, the generation of two-dimensional perovskites through organic cation engineering is avoided.

[0005] Besides crystallization regulation, defect passivation is also crucial for achieving high-quality perovskite films. Most work focuses on passivating defects, either at bulk grain boundaries (GBs) or on the bottom or top surfaces of perovskite films. However, many deep-level defects are often located at GBs and interfaces, leading to severe defect-induced nonradiative recombination. In this context, simultaneously passivating bulk and interface defects is essential for obtaining perovskite films with minimized nonradiative recombination and efficient carrier transport. Considering this, Zhu et al. proposed a depth-dependent regulation strategy to simultaneously repair bulk and interface defects in perovskite films. This suppressed nonradiative recombination losses at both the bulk and interface, resulting in a significant increase in PCE from 21.79% to 24.36%. Xu et al. reported a thermally induced comprehensive passivation strategy that achieved a PCE of 23.0% on an undoped phthalocyanine hole conductor. To maximize defect passivation through multiple chemical bonding modes, it is promising to develop multi-active-site organic salt defect passivators with electron-donating functional groups.

[0006] Therefore, there is an urgent need to develop more effective multi-active-site defect passivators to reduce non-radiative recombination losses in the bulk phase and at the interface. Summary of the Invention

[0007] In view of this, one objective of the present invention is to provide a non-methylammonium perovskite solar cell; another objective of the present invention is to provide a method for preparing a non-methylammonium perovskite solar cell.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] 1. A formammonium-free perovskite solar cell, wherein the perovskite solar cell comprises, from bottom to top, a substrate layer, a lower charge transport layer, a perovskite layer, an upper charge transport layer, and an electrode;

[0010] The lower charge transport layer, from bottom to top, comprises nickel oxide compounds (NiO). x ) film, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) film and aluminum oxide film;

[0011] The perovskite layer, from bottom to top, comprises a perovskite film and an S-methylisothiourea hydroiodic acid (SMI) film, wherein the perovskite film is made by passing FA containing phenformin hydrochloride (PFCl). 0.95 Cs 0.05 PbI3 perovskite precursor solution was spin-coated onto the surface of the underlying charge transport layer;

[0012] The upper charge transport layer, from bottom to top, includes PC. 61 BM film and copper bath (BCP) film.

[0013] Preferably, the base layer is made of ITO.

[0014] Preferably, the electrode is made of metallic silver.

[0015] 2. The above-mentioned method for preparing a methylammonium perovskite solar cell, wherein the preparation method includes the following steps:

[0016] (1) Preparation of the lower charge transport layer on the substrate material: 5~50 mg / mL of nickel oxide compound (NiO) was added. x The nanoparticle solution was spin-coated in air at 2000-5000 rpm onto a cleaned and ultrasonicated substrate for 10-30 seconds, and then annealed at 100-150°C for 10-60 minutes to form a nickel oxide compound (NiO). x The film was transferred to a nitrogen-filled glove box, and a 1-10 mg / mL solution of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) dissolved in chlorobenzene (CB) was spin-coated onto a nickel oxide compound (NiO) at 2000-8000 rpm. xA poly(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) film is formed on the film for 10-30 s. Then, an Al2O3 dispersion is spin-coated onto the poly(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) film at a speed of 2000-8000 rpm for 10-30 s to form an aluminum oxide film, thereby forming a lower charge transport layer on the substrate material.

[0017] (2) Preparation of a perovskite layer on the lower charge transport layer: FA containing PFCl 0.95 Cs 0.05 The PbI3 perovskite precursor solution is spin-coated onto the lower charge transport layer at a speed of 1000-4000 rpm for 10-30 s, followed by spin-coating at a speed of 2000-4000 rpm for another 10-40 s. 3-15 s before the end of spin-coating, 100-200 μL of chlorobenzene (CB) is added dropwise, and the mixture is annealed at 100-200 °C for 10-30 min to form a perovskite film. This forms the perovskite layer on the lower charge transport layer. Then, 0.2-5 mg / mL of S-methylisothiourea hydroiodic acid (SMI) is spin-coated onto the surface of the perovskite layer at a speed of 3000-8000 rpm for 10-30 s, and annealed at 100-150 °C for 1-10 min to form an S-methylisothiourea hydroiodic acid (SMI) film, thus forming the perovskite layer on the lower charge transport layer.

[0018] (3) Preparation of an upper charge transport layer on the perovskite layer: PC dissolved in 10~30 mg / mL chlorobenzene (CB) 61 BM solution was spin-coated onto perovskite films at a speed of 2000-5000 rpm for 10-40 s to form PC. 61 BM membrane, continue filtering the 0.5~5 mg / mL supersaturated solution of copper hydroxide (BCP) dissolved in IPA through PC. 61 A copper bath (BCP) film is formed by spin-coating on a BM film for 10-30 seconds, which can then be used to prepare an upper charge transport layer on the perovskite layer.

[0019] (4) Prepare electrodes on the upper charge transport layer: Vacuum thermal evaporation of 80~100nm metallic silver on the upper charge transport layer to form electrodes, thus obtaining a formammonium perovskite solar cell.

[0020] Preferably, in step (1), the specific method of ultrasonic cleaning is as follows: the substrate material is placed in deionized water, alcohol, acetone and isopropanol in sequence for ultrasonic cleaning for 30~180 min, and then dried and treated with ultraviolet-ozone (UVO) for 10~30 min.

[0021] Preferably, in step (2), the FA 0.95 Cs 0.05 FA in PbI3 perovskite precursor solution 0.95 Cs 0.05 The concentration of PbI3 was 1.3~1.8M;

[0022] The FA 0.95 Cs 0.05 The PbI3 perovskite precursor solution is prepared as follows: FAI, CsI and PbI2 are dissolved in a mixed solvent of DMF and DMSO at a mass ratio of 220~250:16~25:600~700, and stirred until they are mixed evenly. The volume ratio of DMF to DMSO in the mixed solution is 3:1~5:1.

[0023] Preferably, in step (2), the FA containing phenformin hydrochloride (PFCl) 0.95 Cs 0.05 The concentration of phenformin hydrochloride (PFCl) in the PbI3 perovskite precursor solution is 0.2–5 mg / mL.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. This invention discloses a non-methylammonium perovskite solar cell, comprising, from bottom to top, a substrate layer and a lower charge transport layer (comprising, from bottom to top, nickel oxide (NiO)). x Thin films, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) thin films and alumina thin films), perovskite layers, and upper charge transport layers (PC). 61 The invention comprises BM thin films and bath copper phosphate (BCP) thin films, and electrodes. The methylammonium perovskite solar cell of this invention exhibits a power conversion efficiency as high as 24.67%, with improved wet and thermal stability. It also has significant implications for the synergistic regulation of crystallization, bulk phase, and interface defects using organic salt engineering.

[0026] 2. This invention also discloses a method for fabricating a methylammonium-free perovskite solar cell. It proposes a novel intermediate phase that does not involve lead iodide, used to assist in a crystallization strategy. This phase, along with a functionalized multi-active-site salt, passivates defects on the perovskite film surface, simultaneously improving the crystallinity of the perovskite film, reducing its defect density, and releasing residual stress. The fabrication method of this invention enables the production of high-efficiency and high-stability perovskite solar cells, while also possessing the advantages of simplicity, low cost, and high reproducibility.

[0027] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0029] Figure 1 In Figure 1, a is the XRD pattern of perovskite films without PFCl formed at different annealing times, and b is the XRD pattern of perovskite films containing PFCl (Perovskite+PFCl).

[0030] Figure 2 The XRD intensity curves of the 2θ=11.82° δ phase (a), 2θ=12.69° PbI2 phase (b), 2θ=14.00° (001) crystal plane (c), and 2θ=19.82° (011) crystal plane (d) of the unannealed perovskite film without PFCl (Control) and the unannealed perovskite film containing PFCl (PFCl) are shown as time-varying curves. In the figure, Perovskite is the perovskite film without PFCl formed by annealing at 100℃ for 1 min, and Perovskite+PFCl is the perovskite film containing PFCl formed by annealing at 100℃ for 1 min.

[0031] Figure 3 In Figure a, XRD patterns of perovskite films without PFCl (without CB) without the addition of the antisolvent chlorobenzene (CB) are shown. In Figure b, XRD patterns of CsI films, CsI+PFCl films, FAI films, FAI+PFCl films, PbI2 films, PbI2+PFCl films, PFCl films, and perovskite films containing PFCl are shown.

[0032] Figure 4 UV-Vis absorption spectra of PFCl-free perovskite films (a) and PFCl-containing perovskite films (Perovskite+PFCl) (b) prepared for different annealing times; UV-Vis absorption intensity at 780 nm during annealing as a function of time (c); nucleation rate calculated using the first derivative (d); growth rate during annealing from 10 to 45 seconds (e).

[0033] Figure 5 Low-resolution surface (a) and cross-sectional (b) SEM images of perovskite films without PFCl and perovskite films containing PFCl (Perovskite+PFCl) (insets are high-resolution surface and cross-sectional SEM images of standard (Perovskite+PFCl) and modified perovskite films (Perovskite+PFCl)), and histogram of statistical distribution of grain size (c) (D represents average grain size);

[0034] Figure 6 The spatial elemental distribution of the SMI-modified perovskite device measured by ToF-SIMS is shown in (a), the XRD patterns of the perovskite film without SMI modification (Control, the perovskite film prepared in Example 3) and the perovskite film with SMI modification (Perovskite+PFCl+SMI, the perovskite layer prepared in step (3) of Example 1) are shown in (b), and the surface (c) and cross-section (d) of the perovskite film with SMI modification (Perovskite+PFCl+SMI) are shown in (d).

[0035] Figure 7 TRMC consists of standard components (Control, unmodified by PFCl and SMI), PFCl film (PFCL), SMI film (SMI), and perovskite layer modified by PFCl and SMI (PFCl+SMI).

[0036] Figure 8 Steady-state photoluminescence (PL) spectra (a) and TRPL curves (b) of a control, PFCl film (PFCL), SMI film (SMI), and perovskite layer modified with PFCl and SMI (PFCl+SMI) on an ITO substrate; scanning photoluminescence (c) of the control on the ITO substrate; scanning photoluminescence (d) of the PFCl film (PFCL); scanning photoluminescence (e) of the SMI film (SMI); and scanning photoluminescence (f) of the perovskite layer modified with PFCl and SMI (PFCl+SMI).

[0037] Figure 9 The defect density of a control, a PFCl film (PFCL), an SMI film (SMI), and a perovskite layer modified with PFCl and SMI (PFCl+SMI) on an ITO substrate in a hole-only device and an electron-only device.

[0038] Figure 10 The d-spacing value of the (001) plane of the control, PFCl film (PFCL), SMI film (SMI) and perovskite layer modified by PFCl and SMI (PFCl+SMI) on the ITO substrate is a function of the grazing incidence angle.

[0039] Figure 11 JV curves (with tables showing relevant photovoltaic parameters) of the best-performing inverted PSCs on ITO substrates (Control) (a), PFCl film (PFCL) (b), SMI film (SMI) (c) and (d), PCE histograms (Control), PFCl film (PFCL), SMI film (SMI) and PFCl and SMI modified perovskite layer (PFCl+SMI) on ITO substrates) (e), EQE curves and integrated current densities (Control), PFCl film (PFCL), SMI film (SMI) and PFCl and SMI modified perovskite layer (PFCl+SMI) on ITO substrates) (f);

[0040] Figure 12 Stability measurements of unpackaged devices formed on ITO substrates (Control), PFCl film (PFCL), SMI film (SMI), and perovskite layer modified with PFCl and SMI (PFCl+SMI) at 20-30% RH in darkness (a), stability of unpackaged devices under sunlight in N2 (b), and stability evolution of unpackaged devices maintained at 85°C in N2 (c). Detailed Implementation

[0041] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0042] Example 1

[0043] A formaldehyde-free perovskite solar cell comprises, from bottom to top, a substrate layer, a lower charge transport layer, a perovskite layer, an upper charge transport layer, and an electrode, and is fabricated according to the following method:

[0044] (1) Cleaning the substrate material: The ITO substrate is placed in deionized water, alcohol, acetone and isopropanol in sequence for ultrasonic cleaning for 30 min, and then dried and treated with ultraviolet ozone for 20 min.

[0045] (2) Preparation of the lower charge transport layer on the substrate material: First, a NiOx NPs aqueous solution with a concentration of 20 mg / mL was spin-coated onto the ITO substrate material at 5000 rpm in air for 30 s, and then annealed at 150℃ for 10 min to form NiO. x Thin film; secondly, the above-mentioned NiO is formed. x The material after film deposition was transferred to a nitrogen-filled glove box, and a 1 mg / mL PTAA solution (solvent: CB) was injected into NiO at a rate of 6000 rpm. x A poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) film was formed by spin-coating on the substrate for 30 seconds. Then, an aluminum oxide film was formed by spin-coating a 0.4 wt% Al2O3 dispersion (isopropanol (IPA) solvent) on the PTAA film at 5000 rpm for 30 seconds, thereby forming a lower charge transport layer (including NiO from bottom to top) on the substrate material. x Thin films, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) films and aluminum oxide films.

[0046] (3) Preparation of a perovskite layer on the lower charge transport layer: First, 4 mg of phenformin hydrochloride (PFCl) was added to 2 mL of FA 0.95 Cs 0.05PbI3 perovskite precursor solution (concentration of 1.4M, prepared as follows: FAI, CsI and PbI2 are dissolved in a mixed solvent of DMF and DMSO in a volume ratio of 4:1 at a mass ratio of 240:20:650, and stirred until homogeneous) with phenethyl guanidine hydrochloride (PFCl) concentration of 2 mg / mL, shaken for 10 min, and then spin-coated at 2000 rpm for 10 s on the lower charge transport layer prepared in step (2), followed by spin-coating at 4000 rpm for 40 s (6 s before the end of the second spin-coating step, 150 μL of chlorobenzene (CB) is added), annealed at 100℃ for 30 min to form a perovskite film with a thickness of 800 nm; then 0.2 mg / mL S-methylisothiourea hydroiodic acid (SMI) solution (solvent in the solution isopropanol (IPA)) is applied to the surface of the perovskite film at 3000 rpm. Spin-coating at rpm for 30 s and annealing at 100℃ for 1 min can form an S-methylisothiourea hydroiodic acid (SMI) film on the perovskite film, thereby forming a perovskite layer on the lower charge transport layer (from bottom to top, including the perovskite film and the SMI film).

[0047] (4) Preparation of an upper charge transport layer on the perovskite layer: First, PC with a concentration of 23 mg / mL was prepared. 61 BM solution (solvent: CB) was spin-coated onto a perovskite film at 2500 rpm for 40 s to form PC. 61 BM membrane; then, a filtered supersaturated solution of copper bath (BCP) with a concentration of 5 mg / mL (in IPA solvent) was spin-coated onto PC at a speed of 5000 rpm. 61 After 30 seconds on the BM film, it is placed in a drying tower for 5 hours to form a copper bath (BCP) film, thus forming the upper charge transport layer (including PC from bottom to top) on the perovskite layer. 61 BM film and copper bath (BCP) film).

[0048] (5) Prepare electrodes on the upper charge transport layer: Prepare a 90 nm thick metallic silver electrode by vacuum thermal evaporation on the hole transport layer to obtain a methylammonium perovskite solar cell.

[0049] Example 2

[0050] A formaldehyde-free perovskite solar cell comprises, from bottom to top, a substrate layer, a lower charge transport layer, a perovskite layer, an upper charge transport layer, and an electrode, and is fabricated according to the following method:

[0051] (1) Cleaning the substrate material: The ITO substrate is placed in deionized water, alcohol, acetone and isopropanol in sequence for ultrasonic cleaning for 10~180 minXX. After drying, it is treated with ultraviolet ozone for 10~30 min.

[0052] (2) Preparation of the lower charge transport layer on the substrate material: First, nickel oxide (NiO) with a concentration of 50 mg / mL was prepared. x NPs aqueous solution was spin-coated onto an ITO substrate at 5000 rpm in air for 30 s, followed by annealing at 150°C for 60 min to form a nickel oxide compound (NiO). x ) thin film; secondly, the above-mentioned NiO is formed x The material after film deposition was transferred to a nitrogen-filled glove box, and a 10 mg / mL solution of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) (chlorobenzene (CB)) was incubated at 8000 rpm in NiO. x A poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) film was formed by spin-coating on the substrate for 30 seconds. Then, an aluminum oxide film was formed by spin-coating a 0.4 wt% Al2O3 dispersion (isopropanol (IPA) solvent) on the PTAA film at 8000 rpm for 30 seconds, thereby forming a lower charge transport layer (including NiO from bottom to top) on the substrate material. x Thin films, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) films and aluminum oxide films.

[0053] (3) Preparation of a perovskite layer on the lower charge transport layer: First, 4 mg of phenformin hydrochloride (PFCl) was added to 2 mL of FA 0.95 Cs 0.05PbI3 perovskite precursor solution (concentration of 1.8M, prepared as follows: FAI, CsI and PbI2 are dissolved in a mixed solvent of DMF and DMSO in a volume ratio of 5:1 at a mass ratio of 250:16:600, and stirred until homogeneous) with 0.2 mg / mL phenethylguanidine hydrochloride (PFCl), shaken for 10 min, and then spin-coated at 4000 rpm for 30 s on the lower charge transport layer prepared in step (2), and then spin-coated at 4000 rpm for another 40 s (200 μL of chlorobenzene (CB) is added 15 s before the end of the second spin-coating step), and annealed at 200℃ for 30 min to form a perovskite film with a thickness of 800 nm; then 5 mg / mL S-methylisothiourea hydroiodic acid (SMI) solution (the solvent in the solution isopropanol (IPA)) is applied to the surface of the perovskite film at 8000 rpm. Spin coating at rpm for 30 s and annealing at 100℃ for 1 min can form an S-methylisothiourea hydroiodic acid (SMI) film on the perovskite film, thereby forming a perovskite layer on the lower charge transport layer (from bottom to top, including the perovskite film and the SMI film).

[0054] (4) Preparation of an upper charge transport layer on the perovskite layer: First, PC with a concentration of 30 mg / mL was prepared. 61 BM solution (solvent: CB) was spin-coated onto a perovskite film at 5000 rpm for 40 s to form PC. 61 BM membrane; then, a filtered supersaturated solution of copper bath (BCP) with a concentration of 5 mg / mL (in IPA solvent) was spin-coated onto PC at a speed of 5000 rpm. 61 After 30 seconds on the BM film, it is placed in a drying tower for 5 hours to form a copper bath (BCP) film, thus forming the upper charge transport layer (including PC from bottom to top) on the perovskite layer. 61 BM film and copper bath (BCP) film).

[0055] (5) Prepare electrodes on the upper charge transport layer: Prepare a 100 nm thick metallic silver electrode by vacuum thermal evaporation on the hole transport layer to obtain a methylammonium perovskite solar cell.

[0056] Example 3

[0057] A formaldehyde-free perovskite solar cell comprises, from bottom to top, a substrate layer, a lower charge transport layer, a perovskite layer, an upper charge transport layer, and an electrode, and is fabricated according to the following method:

[0058] (1) Cleaning the substrate material: The ITO substrate is placed in deionized water, alcohol, acetone and isopropanol in sequence for ultrasonic cleaning for 180 min, and then dried and treated with ultraviolet ozone for 30 min.

[0059] (2) Preparation of the lower charge transport layer on the substrate material: First, an aqueous solution of oxygen compound (NiOx) NPs with a concentration of 5 mg / mL was spin-coated onto the ITO substrate material at 2000 rpm for 10 s in air, and then annealed at 100℃ for 10 min to form oxygen compound (NiOx). x） Thin film; secondly, the above-mentioned NiO is formed. x The material after film deposition was transferred to a nitrogen-filled glove box, and a 1 mg / mL poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) solution (solvent: CB) was incubated at 2000 rpm in NiO. x Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) film was formed by spin-coating on the film for 10 s; then, an aluminum oxide film was formed by spin-coating a 0.4 wt% Al2O3 dispersion (isopropanol (IPA) solvent) on the PTAA film at 2000 rpm for 10 s, thereby forming a lower charge transport layer on the substrate material (which, from bottom to top, includes nickel oxide compounds (NiO)). x ) film, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) film and aluminum oxide film.

[0060] (3) Preparation of a perovskite layer on the lower charge transport layer: First, 4 mg of phenformin hydrochloride (PFCl) was added to 0.8 mL of FA 0.95 Cs 0.05The PbI3 perovskite precursor solution (concentration of 1.3M, prepared as follows: FAI, CsI and PbI2 are dissolved in a mixed solvent of DMF and DMSO in a volume ratio of 3:1 at a mass ratio of 220:25:700, and stirred until homogeneous) is mixed with phenformin hydrochloride (PFCl) at a concentration of 5 mg / mL. After shaking for 10 min, spin-coating is performed on the lower charge transport layer prepared in step (2) at a speed of 1000 rpm for 10 s, followed by spin-coating at a speed of 2000 rpm for 10 s. (100 μL of chlorobenzene (CB) is added 3 s before the end of the second spin-coating step). The mixture is then annealed at 100℃ for 10 min to form a perovskite film with a thickness of 800 nm. Thus, a perovskite film can be formed on the lower charge transport layer. Then, 0.2 A solution of S-methylisothiourea hydroiodic acid (SMI) at a concentration of mg / mL (with isopropanol (IPA) as the solvent) is spin-coated onto the surface of a perovskite film at 3000 rpm for 10 s, followed by annealing at 100°C for 1 min. This process forms an SMI film on the perovskite film, thereby creating a perovskite layer on the underlying charge transport layer (which, from bottom to top, consists of the perovskite film and the SMI film).

[0061] (4) Preparation of an upper charge transport layer on the perovskite layer: First, PC with a concentration of 10 mg / mL was prepared. 61 BM solution (chlorobenzene (CB) as solvent) was spin-coated onto a perovskite film at 2000 rpm for 10 s to form PC. 61 BM membrane; then, a filtered supersaturated solution of copper hydroxide (BCP) at a concentration of 0.5 mg / mL (solvent IPA) was spin-coated onto PC at a speed of 5000 rpm. 61 After 10 s on the BM film, it is placed in a drying tower for 5 h to form a copper bath (BCP) film, thus forming the upper charge transport layer (including PC from bottom to top) on the perovskite layer. 61 BM film and copper bath (BCP) film).

[0062] (5) Prepare electrodes on the upper charge transport layer: Prepare 80 nm thick metallic silver electrodes by vacuum thermal evaporation on the hole transport layer to obtain a methylammonium perovskite solar cell.

[0063] Performance testing

[0064] Perovskite films containing PFCl were prepared with different annealing times (the "annealing for 1 min" in step (3) of Example 1 was changed sequentially to "annealing for 0 s, 1 s, 5 s, 10 s, 30 s, 60 s and 300 s", and the rest of the method was the same as step (3) in Example 1) and perovskite films without PFCl were prepared with different annealing times (the "adding 4 mg of PFCl to FA" method was used in the perovskite films containing PFCl prepared with different annealing times). 0.95 Cs 0.05 "PbI3 perovskite precursor solution" can be directly replaced with "FA". 0.95 Cs 0.05 PbI3 perovskite precursor solution”). Figure 1 Image a shows the XRD patterns of perovskite films without PFCl formed at different annealing times, and image b shows the XRD patterns of perovskite films containing PFCl (Perovskite + PFCl). Figure 1 It can be seen that in the preparation of perovskite thin films, FA 0.95 Cs 0.05 After adding phenformin hydrochloride (PFCl) to the PbI3 perovskite precursor solution, the crystallization kinetics of the resulting black phase perovskite film changed significantly with the annealing time.

[0065] Figure 2 The XRD intensity curves of the 2θ=11.82° δ phase (a), 2θ=12.69° PbI2 phase (b), 2θ=14.00° (001) crystal plane (c), and 2θ=19.82° (011) crystal plane (d) of the unannealed perovskite film without PFCl (Control) and the unannealed perovskite film containing PFCl (PFCl) are shown as time-varying curves. Perovskite represents the perovskite film without PFCl formed after annealing at 100℃ for 1 min, and Perovskite+PFCl represents the perovskite film containing PFCl formed after annealing at 100℃ for 1 min. Figure 2 It can be seen that a black phase appeared in the PFCl-modified perovskite film before annealing, and the yellow intermediate phase was significantly suppressed. However, as annealing proceeded, the standard sample (perovskite film without PFCl) precipitated PbI2 phase, while the modified film (perovskite film with PFCl) did not, indicating that the crystallinity of the perovskite in the modified film was significantly enhanced.

[0066] Perovskite films without PFCl (preparation method is the same as step (3) of Example 3, except that phenformin hydrochloride (PFCl) and chlorobenzene (CB) are not added) and perovskite films containing PFCl (perovskite+PFCl with CB) without adding the antisolvent chlorobenzene (CB) (same as step (3) of Example 3, except that chlorobenzene (CB) is not added) were prepared. The XRD patterns of the products are shown below. Figure 3 As shown in Figure a, the CsI thin film (prepared by the same method as step (3) of Example 3, except that FA containing PFCl is used) 0.95 Cs 0.05 The PbI3 perovskite precursor solution was replaced with a CsI solution of the same concentration; the CsI+PFCl film was prepared using the same method as step (3) of Example 3, except that the PFCl-containing FA was replaced with a CsI solution of the same concentration. 0.95 Cs 0.05 The PbI3 perovskite precursor solution was replaced with CsI and PFCl solutions of the same concentration; the FAI film was prepared using the same method as step (3) of Example 3, except that the PFCl-containing FAI film was replaced with a CsI and PFCl solution. 0.95 Cs 0.05 The PbI3 perovskite precursor solution was replaced with a FAI solution of the same concentration), and the FAI+PFCl film was prepared using the same method as step (3) of Example 3, except that the PFCl-containing FAI+PFCl film was replaced with a FAI+PFCl solution of the same concentration. 0.95 Cs 0.05 The PbI3 perovskite precursor solution was replaced with FAI and PFCl solutions of the same concentration; the PbI2 film was prepared using the same method as step (3) of Example 3, except that the PFCl-containing FAI was replaced with a solution containing PFCl. 0.95 Cs 0.05 The PbI3 perovskite precursor solution was replaced with a PbI2 solution of the same concentration; the PbI2+PFCl film was prepared using the same method as step (3) of Example 3, except that the PFCl-containing FA was replaced with a PbI2+PFCl-containing ... 0.95 Cs 0.05 The PbI3 perovskite precursor solution was replaced with a PbI2 and PFCl solution of the same concentration; the PFCl film was prepared using the same method as step (3) of Example 3, except that the PFCl-containing FA was replaced with a PbI2 and PFCl solution. 0.95 Cs 0.05 The XRD patterns of the PbI3 perovskite precursor solution (replaced with PFCl solution of the same concentration) and the perovskite film containing PFCl (Perovskite + PFCl) are shown below. Figure 3 As shown in b. From Figure 3It is known that a novel intermediate phase (PFCl-FAI) exists in the modified perovskite film (perovskite film containing PFCl + PFCl) prepared without the addition of antisolvent (CB).

[0067] Figure 4 The UV-Vis absorption spectra of PFCl-free perovskite films (a) and PFCl-containing perovskite films (perovskite+PFCl) (b) prepared for different annealing times are shown. The UV-Vis absorption intensity at 780 nm during annealing is also shown as a function of time (c). The corresponding nucleation rate is calculated using the first derivative (d), and the growth rate during annealing (10–45 seconds) is shown (e). Figure 4 It can be seen that adding PFCl significantly accelerates the nucleation rate of the black phase in the perovskite film and slows down the grain growth rate.

[0068] Figure 5 Low-resolution SEM images (a) and (b) of the surface and cross-section of PFCl-free and PFCl-containing perovskite films (insets show high-resolution surface and cross-sectional SEM images of the standard (Perovskite+PFCl) and modified perovskite films (Perovskite+PFCl)), and a histogram of the statistical distribution of grain size (c) (D represents the average grain size). Figure 5 It can be seen that the grain size of the perovskite film modified with PFCl is significantly increased, and the interface of the film is more flat.

[0069] Figure 6 The images show the spatial elemental distribution of the SMI-modified perovskite layer measured by ToF-SIMS (a), XRD patterns of the unmodified perovskite film (Control, the perovskite film prepared in Example 3) and the SMI-modified perovskite film (Perovskite+PFCl+SMI, the perovskite layer prepared in step (3) of Example 1) (b), and SEM images of the surface (c) and cross-section (d) of the SMI-modified perovskite film (Perovskite+PFCl+SMI). Figure 6 It can be seen that the SMI-modified film is mainly located on the upper surface of the perovskite film. SMI does not significantly change the crystallinity and grain size of perovskite, but the interface of the perovskite film will be smoother.

[0070] Figure 7TRMC consists of standard (Control, unmodified with PFCl and SMI), PFCl film (PFCl), SMI film (SMI), and a perovskite layer modified with PFCl and SMI (PFCl+SMI). Figure 7 It can be seen that the carrier mobility of the perovskite layer is significantly improved after synergistic modification (PFCl+SMI).

[0071] Figure 8 The images show the steady-state photoluminescence (PL) spectrum (a) and TRPL curve (b) of a control, a PFCl film (PFCL), an SMI film (SMI), and a perovskite layer modified with PFCl and SMI (PFCl+SMI) on an ITO substrate; the scanning photoluminescence (SPR) spectrum (c) of the control on the ITO substrate; the SPR spectrum (d) of the PFCl film (PFCL); the SPR spectrum (e) of the SMI film (SMI); and the SPR spectrum (f) of the perovskite layer modified with PFCl and SMI (PFCl+SMI). Figure 8 It can be seen that the perovskite layer after synergistic modification (PFCl+SMI) exhibits the strongest fluorescence emission and the longest carrier lifetime in the thin film.

[0072] Figure 9 The defect densities of a control, a PFCl film (PFCL), an SMI film (SMI), and a perovskite layer modified with PFCl and SMI (PFCl+SMI) on an ITO substrate are shown in both a hole-only device and an electron-only device. Figure 9 It can be seen that the perovskite layer with the synergistic modification (PFCl+SMI) has the lowest internal defect density.

[0073] Figure 10 The d-spacer value of the (001) plane of the control, PFCl film (PFCL), SMI film (SMI), and perovskite layer modified with PFCl and SMI (PFCl+SMI) on the ITO substrate is calculated as a function of the grazing incidence angle. Figure 10 It can be seen that the residual stress inside the perovskite layer after synergistic modification (PFCl+SMI) is the smallest.

[0074] Figure 11JV curves (with tables showing relevant photovoltaic parameters) of the best-performing inverted PSCs on ITO substrates (Control) (a), PFCl film (PFCL) (b), SMI film (SMI) (c), and (d) (e), PCE histograms (Control, PFCl film (PFCL), SMI film (SMI), and PFCl+SMI modified perovskite layer) on ITO substrates) are presented, along with EQE curves and integrated current densities (Control, PFCl film (PFCL), SMI film (SMI), and PFCl+SMI modified perovskite layer) on ITO substrates (f). Twenty individual cells were statistically analyzed for each device. Figure 11 It can be seen that the perovskite layer with synergistic modification (PFCl+SMI) has the highest efficiency and the best repeatability, with an efficiency of up to 24.67%.

[0075] Figure 12 Stability measurements of unpackaged devices formed on ITO substrates using a control, a PFCl film (PFCL), an SMI film (SMI), and a PFCl+SMI modified perovskite layer (PFCl+SMI) in darkness at 20–30% RH (a); stability of the unpackaged device under sunlight exposure in N2 (b); and stability evolution of the unpackaged device at 85°C in N2 (c). Figure 12 It can be seen that after being stored in air with a relative humidity of 20-30% for 2976 hours, continuously illuminated in nitrogen for 1008 hours, and continuously heated at 85°C for 864 hours, the unpackaged PFCl+SMI device maintained 90%, 84%, and 90% of its initial efficiency, respectively.

[0076] In summary, this invention discloses a non-methylammonium perovskite solar cell, which, from bottom to top, comprises a substrate layer and a lower charge transport layer (from bottom to top, comprising NiO). x Thin film, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) thin film and alumina thin film), perovskite layer, upper charge transport layer (PC) 61The invention discloses a BM thin film and a BCP thin film, along with electrodes. The BM-free perovskite solar cell of this invention exhibits a high power conversion efficiency of 24.67%, with improved wet and thermal stability. It also has significant research implications for the synergistic regulation of crystallization, bulk phase, and interface defects using organic salt engineering. This invention also discloses a method for preparing a BM-free perovskite solar cell, proposing a novel intermediate phase that does not involve lead iodide, used to assist in a crystallization strategy. This phase synergistically functions with multi-active-site salts to passivate defects on the perovskite film surface, simultaneously improving the crystallization of the perovskite film, reducing its defect density, and releasing residual stress. The preparation method of this invention enables high-efficiency and high-stability perovskite solar cells, while also possessing the advantages of simplicity, low cost, and high reproducibility.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A non-methylammonium perovskite solar cell, characterized in that, The perovskite solar cell comprises, from bottom to top, a substrate layer, a lower charge transport layer, a perovskite layer, an upper charge transport layer, and an electrode; The lower charge transport layer, from bottom to top, comprises a nickel oxide film, a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] film, and an aluminum oxide film; The perovskite layer comprises, from bottom to top, a perovskite film and an S-methylisothiourea hydroiodic acid film, wherein the perovskite film is made by using FA containing phenformin hydrochloride. 0.95 Cs 0.05 PbI3 perovskite precursor solution was spin-coated onto the surface of the underlying charge transport layer; The upper charge transport layer, from bottom to top, includes PC. 61 BM film and copper bath film.

2. The non-methylammonium perovskite solar cell according to claim 1, characterized in that, The base layer is made of ITO.

3. The non-methylammonium perovskite solar cell according to claim 1, characterized in that, The electrode is made of metallic silver.

4. The method for preparing the methylammonium perovskite solar cell according to any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: (1) Preparation of the lower charge transport layer on the substrate material: A nickel oxide nanoparticle solution of 5-50 mg / mL was spin-coated in air at 2000-5000 rpm onto a cleaned and ultrasonicated substrate material for 10-30 s. The substrate was then annealed at 100-150℃ for 10-60 min to form a nickel oxide film. The film was transferred to a nitrogen-filled glove box. A poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] solution of 1-10 mg / mL dissolved in chlorobenzene was spin-coated onto the nickel oxide film at 2000-8000 rpm for 10-30 s to form a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] film. An Al2O3 dispersion was then spin-coated onto the poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] film at 2000-8000 rpm for 10-30 s. Alumina thin film is formed, thereby forming a lower charge transport layer on the substrate material; (2) Fabrication of a perovskite layer on the lower charge transport layer: FA containing phenformin hydrochloride 0.95 Cs 0.05 The PbI3 perovskite precursor solution is spin-coated onto the lower charge transport layer at a speed of 1000-4000 rpm for 10-30 s, followed by spin-coating at 2000-4000 rpm for another 10-40 s. 3-15 s before the end of spin-coating, 100-200 μL of chlorobenzene is added dropwise, and the mixture is annealed at 100-200 °C for 10-30 min to form a perovskite film. This forms the perovskite layer on the lower charge transport layer. Then, 0.2-5 mg / mL of S-methylisothiourea hydroiodic acid is spin-coated onto the surface of the perovskite layer at a speed of 3000-8000 rpm for 10-30 s, and annealed at 100-150 °C for 1-10 min to form an S-methylisothiourea hydroiodic acid film, thus forming the perovskite layer on the lower charge transport layer. (3) Preparation of an upper charge transport layer on the perovskite layer: PC dissolved in 10~30 mg / mL chlorobenzene 61 BM solution was spin-coated onto perovskite films at a speed of 2000-5000 rpm for 10-40 s to form PC. 61 BM membrane, continue filtering the 0.5~5 mg / mL supersaturated copper hydroxide solution dissolved in IPA through PC. 61 A copper bath film is formed by spin-coating a BM film for 10-30 seconds, which can then be used to prepare an upper charge transport layer on the perovskite layer. (4) Prepare electrodes on the upper charge transport layer: Vacuum thermal evaporation of 80~100nm metallic silver on the upper charge transport layer to form electrodes, thus obtaining a formammonium perovskite solar cell.

5. The preparation method according to claim 4, characterized in that, In step (1), the specific method of ultrasonic cleaning is as follows: the substrate material is placed in deionized water, alcohol, acetone and isopropanol in sequence for ultrasonic cleaning for 30~180min, and then dried and treated with ultraviolet-ozone for 10~30min.

6. The preparation method according to claim 4, characterized in that, In step (2), the FA 0.95 Cs 0.05 FA in PbI3 perovskite precursor solution 0.95 Cs 0.05 The concentration of PbI3 was 1.3~1.8M; The FA 0.95 Cs 0.05 The PbI3 perovskite precursor solution is prepared as follows: FAI, CsI and PbI2 are dissolved in a mixed solvent of DMF and DMSO at a mass ratio of 220~250:16~25:600~700, and stirred until they are mixed evenly. The volume ratio of DMF to DMSO in the mixed solution is 3:1~5:

1.

7. The preparation method according to claim 4, characterized in that, In step (2), the FA containing phenformin hydrochloride 0.95 Cs 0.05 The concentration of phenformin hydrochloride in the PbI3 perovskite precursor solution is 0.2–5 mg / mL.

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